The statement summary read, "The Supervisory Board of Volkswagen AG emphatically repudiates the assertions made by Ferdinand Piëch as reported recently in the media."

The main body of the English-language version posted on the group's corporate website said:

A similar account, which alongside the former CEO was directed above all against a number of current and former members of the Executive Committee of the Supervisory Board, was already given by Ferdinand Piëch in spring 2016 in the context of the internal, independent investigations.

This account was subsequently examined in close detail by law firm Jones Day. No evidence was forthcoming indicating the accuracy of these allegations, which were classified as implausible overall.

In addition, all affected members of the Executive Committee of the Supervisory Board, acting independently of each other, have unequivocally and emphatically rejected all assertions made by Ferdinand Piëch as untrue.

The Board of Management will carefully weigh the possibility of measures and claims against Mr. Piëch.

To be clear, that means that VW Group is considering taking legal action against the scion of the family that founded the company, who ran it as chairman and CEO from 1993 until he was deposed in April 2015.

The impetus for this remarkable eruption, as reported by the Associated Press, was the pre-publication release of an article from Bild am Sonntag, the German business newspaper.

That article asserted that Piech had given early warnings to four members of the supervisory board about the use of "defeat device" software in its diesel vehicles.